It's time to break free from the tyranny of a tethered mouse and keyboard...

CAN YOU remember the days before television remote controls and cordless telephones? How primitive the idea of hitting buttons on the TV to change channels, or remaining tethered to the telephone when making a call, seems today! It was inevitable that the personal computer, being touted as `the' information appliance of this Century, would also join the ranks of the "freedom fighters" and enable its users to break free from the bondage of fixed-length wires.

It is almost a decade since Logitech, the Swiss company that specialises in PC interface devices unveiled the world's first cordless mouse, the "MouseMan". But it is only in the last year or two that cordless keyboards and pointing devices like the mouse and the joystick have become easily available in this country. They are still pricey options compared to their wired parents (an optical mouse or keyboard costs five to 10 times more) but then freedom never came cheap! And having sampled the convenience of wireless interfaces to the PC, one will never go back to the old ways.

Logitech's first technical advance was to do away with the ball and rollers in the mouse  mechanical components which tend to wear out or become sluggish with time. To replace these, the company used an optical sensor linked to a tiny digital signal processor (DSP). The combo measured tiny changes in position and translated them into movements of the cursor on the screen.

Then came radio technology which enabled users to throw away the cord linking the mouse to the PC. In its place, one had to plug a tiny wireless receiver into the USB port of the PC which communicated with the transmitter in the cordless mouse. This works much like the infra-red link used by a TV remote  with one important difference. Unlike the remote, the cordless mouse need not be in the clear "line of sight" of the receiver. Radio waves in the frequency band used (27 MHz) can get around corners as long as the mouse is operated within 2 to 2.5 metres of the PC. The cordless mouse also uses a special 12 bit security code so that it can uniquely identify the PC and will not get confused by other cordless devices being operated in the vicinity. Similar technology has untethered the keyboard and the trackball besides creating a host of cordless interactive gaming devices.

While Logitech has pioneered some of these technologies, there are others players in the wireless PC interface business. UC-Logic technologies offers a SuperPen  a replacement for mouse or trackball that is used to write on a cordless pressure - sensitive tablet. It is a great tool for pointing, clicking, browsing, drawing  and writing text in freehand which the PC converts into a text file. Another variant of the cordless mouse is the FinRing, a tiny wearable mouse that is worn on the forefinger. It communicates with the PC at a relatively higher frequency of around 400 MHz.

And what of the future? Many makers of pointing devices are putting their money into the emerging wireless technology known as Bluetooth. This will increase the effective range to between 10 and 20 metres. Bluetooth has the advantage that it can be used to communicate with a variety of other wireless devices such as mobile phones and hand held computers. When that happens, one can truly say, "It's Independence Day  from the tyranny of the tethered PC."